Add global m to your fun2; I also used point-wise multiplication and exponentiation to make it work.
function T = fun(theta)
global m
m = theta^2;
T = quad(@fun2,0,1)
end
function out = fun2(t)
global m
out=( (1-m*t.^2).*(1-t.^2) );
end
Alternatively, you could define fun2 as an anonymous function; note that here fun2 is already a function handle, so you have to pass with without the @ to quad:
function T = fun(theta)
global m
m = theta^2;
fun2 = @(t) (1-m*t.^2).*(1-t.^2)
T = quad(fun2,0,1)
end
